Railway-traffic-controlling apparatus



L. V. LEWIS.

RAILWAY TRAFFIC CONTROLLING APPARATUS. APPLICATION FILED Nov 25, 1918.

1,377, 1 37. Paifienwd y & 1921,

3 SHEETS-SHEET l.

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7 a 3 F away ak-eaweai Iii INVENTOF-i d WQ'4AQLMIMA4 L. V. LEWIS.

RAILWAY TRAFFIC CONTROLLING APPARATUS.

APPLXCATION FILED NOV, 25, I818- I Patented May 3, 1921.

3 SHEETSSHEET 2- when L. V. LEWIS.

RAiLW/W TRAFFIC CONTROLLING APPARATUS. APPLICATION FILED NOV, 25. 1918.

Patented May 3, 1592]..

3 SHEETS--SHEET 3.

UNITED STATES PATENT OFFICE.

LLOYD V. LEWIS, OF EDGEWOOD BOROUGH, IPENNSYLVANIA, ASSIGNOR TO THE UNION SWITCH & SIGNAL COMPANY IORATION OF PENNSYLVANIA.

, OF SWISSV'ALE, PENNSYLVANIA, A COR- RAILWAY-TRAFFIC-CONTROLLING APPARATUS.

Application filed November To all whom, may concern:-

Be it known that'I, LLoYn V. Lewis, a citizen of the United States, residing at Edgewood Borough, in the county'of Allegheny and State of Pennsylvania, have in vented certain new andnuseful Improve ments in Railway-Trafiic-ControllingApparatus, of which the following is a specification.

My invention relates to railway traiiic controlling apparatus, and has for an object the provision of simple and reliable means for transmitting to a railway vehicle indications of trafiic conditions in. advance without mechanical or electrical contact between devices on the vehicle and devices in the trackway.

I will describe three forms of apparatus embodying my invention, and will then 'point out the novel features thereof in claims.

In the accompanying drawings, Figure 1 is a diagrammatic view showing one form of railwa v traflic controlling apparatus embodying my invention. Figs. 2 and 3 are views similar to Fig. 1, but showing modifications of the vehicle-carried apparatus also en'ibodying my invention.

Similar reference characters refer to similar parts in each of the views.

Referring first to Fig. 1, the reference characters H- and H designate the track.

rails of a railway, which rails are divided into block sections A,B, B-C, etc, by in: sulated joints 2. Each section is provided with a track circuit comprising the two track rails of the section, a track battery 3, and a track relay designated by the reference character F with an exponent- (oi-responding to the location of the relay. These track relays are employed to control the indications transmitted to the vehicles traveling along the railway, in a manner herein' after explained.

Located in block section AB is a vehicle V (a railway car or train) which is represented by two axles and'two pairs of wheels. This vehicle is provided with apparatus wh ch I will now describe.

Meunted on the vehicle is an electron tube 1i comprising a vacuum Lube 4, containing a ilament 5, a plate 3, and a grid 7 I Specification of Letters Patent.

Patented May 3, 1921. 25, 1918. Serial No. 263,969;

between the filament and the plate. The filament 5 is constantly heated to incandescence by a battery 8 through a circuit which is obvious from the drawing. Between the grid 7 and filamentfi an alternating difference of potential is maintained due tosustainetl oscillations in a circuit a which is tuned to resonance at a predetermined frequency, and the oscillations in this circuit a are in turn maintained by a portion of the energy output from the plate circuit of the electron tube K. Circuit 0; comprises a con- ;dens'er l1 and the secondary 12 of atransformer T The terminals of the condenser are connected with the filament and grid respectively of the electron tube K, a blocking condenser 9 being included in the connection as shown. A high resistance 10 is optiona'lly connected in multiple with the condenser 9 for the purpose of limiting the amplitude of the oscillations in circuit a. The plate circuit for electron tube K is from a battery 13 through the filament, grid and a transformer T, so that oscillations are sustained in circuit b by energy from the plate circuit. Circuit Z) includes the secondary of transformer T, a winding 2-1 of relay R, a condenser 22, and a coil on a laminated soft iron core 24. The core 24 is U-shaped as shown, with its legs projecting downwardly, and the plane of the core is parallel to the track rails Hand H. Located at certain points in the trackway are bars D of soft iron, each of which bars is also parallel with the track rails. and is so positioned that it is directly under and close to the open ends of core 24 as the vehicle passes over the bar. The elements in circuit b are so proportioned that when core 2% is not influenced by a bar D, this circuit is exist in circuit b.

When core 24 passes over a trackway bar D, however, the reluctance of this" core is considerably reduced, so that the inductance of coil 23 is greatly increased. Circuit 7) is then not resonant at the given frequency, hence the amplitude of the oscillations in this circuit is reatly reduced.

"Relay R is of the in uction motor type,

comprising the two stator windings 17 and 21,- a rotor 25, and a contact 26 which is operated'by the rotor and closed only when the relay is effectively energized." Current is supplied to winding 17 directly froih the electron tube K, and when circuit b is resonant at the same frequency as circuit a, current is also supplied to winding 21 of such value that the relay is effectively energized. Since circuit 1; is tuned to resonance, the current in winding 21 is evidently in phase with the alternating cur-. rent .in the plate circuit of electron tube K. Condenser I16 and Winding 17 aretuned'to resonance at the given frequency, so that.

. the electromotiveforce across 17 s in phasem with'this current, and since winding 17 is inductive, the current through winding 17 will have greater amplitude and difier widely in phase from the total plate cir- -cuit current and hence will be in approximate quadrature with the current 1n winding'21'. \Vh'en, however, the core 24 passes over a trackway bar D so .that the resonance'of circuit 6 at the given frequency is destroyed, the current in relaywinding 21 is reduced to such a degree that relay R is no longer eifectively energihgd, and contact. 26 then opens. Preferably the two windings 17 and 21 of relay R are made unequal, so that the larger portion of the total energyrequired to operate this relay is obtained directly fromthe' plate circuit of the electron tube K, and but a small ortion is obtained from circuit 6. The e ective resistance of circuit b may thus be kept at a low value and thereby sharp resonance obtained.

So far as concerns the apparatusv thus far described, it will be seen that relay It iseliectively energized to close its cont-act26' at all times except when core 24 is directly over one of the trackway bars D. Relay R controls a relay R, which latter relay is provided with a pick-up circuit-and a stick circuit. The stick circuit for relay R is from a battery 27. through wires 28, 29, winding of relay R, wires 30 .and 31, contact 32 of relay R, wire 33, cont-act 26 of relay R, and wire 34 to battery 27. It will be seen, therefore, that when relay R is once closed or energized, it will're-main energized as long as relay R is effectively energized, .but that when relay R once hedenergized.

comes denergized, owing to the opening of contact 26, relay R will remain: deenergized, even after contact 26 closes, until the pick-up circuit for. relay R becomes closed. The pick-up circuit for relay R is controlled-by a contact 35 of an induction motor relay R the circuit being from battery 27, through wires 28 and 29, winding of relay R, wires 30 and 36, contact of relay R and wire 37 to battery 27. It follows that when relay R is energized, relay R will continue to be energized, regardless of the position of contact 26, or relay R will become energized it it is then Relay R is of the induction motor type comprising two stator windings 38 and '39. These windings are sup lied with energy from the plate circuit oi an electron tube K. The plate circuit for electron tube K is .from battery 13, through wires 14 and 40, relay winding 38, relay winding 39 and condenser 41 in multiple, wire 42, electron tube K, and wire 43 to battery 13. The grid of the electron tube K." is rovided :with an oscillatin circuit'which 1S designated by the reerence character 0, and which circuit includes a winding 44 on a laminated soft iron core 45 and a condenser 46. This circuit 0 is tuned to resonance at a predetermined frequency, such as 60 cycles. The terminals of the condenser 46 are connected with the filament and grid, respectively, of electron tube K, a blocking-condenser 47 being inserted in this conne'ction, as shown. The-core 45 is U-shaped, with its legs projecting downwardly, and is 'arranged transversely with respect to the track, as shown'inthe drawing. Located in the trackway adjacent'each bar I) is a conductor W, which is at times supplied with alternating current by eans hereinafter explained. \Vhen the vehicle carried 'core 45 passes over a conductor W iii-which 6O cycle current is flowing, part of the magnetic lines of force surrounding the conductor pass throughthe core 45 and so induce an alternating potential in the coil 44, whereupon sustained oscillations are produced in the resonant circuit 0. This r duces an alternating difference of potei ti 1 between the grid and filament of the electron tubevK, whereby an alternating compqnent is produced in the current in the plate circuit of K which contains the windings of relay R Since this relay R is of the well known induction motor type, it is not aflected by the continuous or steady component of the current in this circuit. but by reason of condenser 41' connected across the terminals of winding 39, the alternating components of the currents through windings 38 and 39 are dis laced in'phase to cause the rotor of relay 2 to close its contact 35.

Relay Pt controls a brake application vmagnet M, the circuit being from battery 27,

through wires 28 and 48, winding of magnet M, wire d9, contact 50 of relay R, and wire 51 to battery 27. The magnet M controls brake application apparatus of any suitable form, in such manner that an automatic application of the brakes occurs whenever this magnet becomes deenergized.

Each block section is rovided with one of the bars D, which bar is located at maximum braking distance .in the rear of the entrance end of the section. Adjacent to each of the bars D is one of the conductors \V, this conductor preferably extending a short distance beyond each end of the adjacent 'bar D. Each conductor is supplied at times with alternating current of suitable frequency (hereinbefore assumed to be cycles), this supply being .controlledby the track relay for the corresponding section. For example, the ends of the con- ,ductor IV in the rear of point B are connected with the terminals of the secondary of a transformer E, and the circuit for the primary of this transformer is 'from the" secondary of transformer J through con tact 52 of track relay F wire,53, primary of transformer E, and lwire 54 to the secondary of transformer J Conductor W' in the rear of location C is similarly supplied with current from a transformer J9, this supply being controlled by. track relay F i. The primary of each transformer J is connected with a transmission line L, which line is constantly supplied with alternating current from a suitablesource, such as a generator G. v

The operation of the apparatus shown in Fi 1, is as follows: U

he section immediately in advance of location C being occupied by a vehicle V, track relay J c is denergized; but inasmuch as block section B-C is unoccupied, relay F is energized so that the conductor W controlled by this relay is sup lied with alt'rnating current. Vehicle is assumed to have ust entered block section A-B. Relay R on this vehicle is, of course, energized and it is also assumed that relay R has been energized so that its stick circuit-is held closed by contact 26. Brake magnet M is consequently energized, so that the vehicle is free to proceed into block section A-B. When the vehicle reaches such a position that the core 24 passes over the trackway bar I), relay R will become dciinergized, so

that its contact 26 will open. Just before "this occurs, however, core45 will pass into the magnetic field surrounding the conductor W, so that relay R will become energized, thus closing at contact 35 the pickup circuit for relay B. This latter relay will, therefore, remainenergized as long as relay R- isdenergized, so that brake magnet M will continue to be energized and no automatic application of the brakes will occur. Vehicle V can, consequently, proceed into block section B-C without interference on the part of the automatic apparatus.

Inasmuch as track relay-I is deenergized, the conductor \V in the rear of location C is not suppliedwith current. It follows that when vehicle V reaches such point that its core 24; passes over the bar D in block section B-C, the consequent opening of contact 26 of relay. R will permit stick relay R to open, and that upon leaving the bar this stick relay will remain open, becauseits pick-up circuit is open at contact 35. The opening of relay R will. deenergize magnet M so that an automatic application of the brakes will immediately occur, so that the vehicle will be brought to a stop, before it reaches location C.

In order to allow the vehicle to proceed after an automatic brake application has occurred, a push button 76 is provided which is normally open butqwhich, when closed, closes a shunt around contact 35 of relay R and so closes the pick-up circuit for relay It even thou h rela R is dener ized. This b y b push button is preferably located at such a place on the vehicle that it is accessible only from the ground, thus requiring the vehicle to come to rest before the button can be oprelay R will energize magnet M so that the brakeswill again be released and the vehicle may proceed.

In the system shown in Fig. 1, the frequency to which circuit wis tuned may be chosen so as to produce the maximum effect in circuit 6, with a slight change in inductance of coil 23. The frequency to which circuits w and bare thus tuned is not, necessarily, the same as the frequency of the current supplied to the trackway conductors Vt". Circuit 0 may be so designed as to respond to a wide variation in the frequency of the 'current induced therein, so that relay It" will operate reliably when circuit 0 is supplied wlth energy from a commerical 60 cycle source of current subject to considerable variation in frequency.

Referring now to Fig. 2, the trackway 4 apparatus shown in this view is the same as that shown in Fig. 1. As for the vehiclecarried apparatus, the cores 24 and 45 and the coils thereon are the same as those shown in Fig. l, and the electron tube K is likewise the same. The grid circuit for electron tube K including the oscillating circuit a is the same as the corresponding circuit in F i 1, but the plate circuit is somewhat ditlerent. This plate circuit in Fig. 2 is from battery 13, through wires 14 and 55, primary of transformer T, wire 18,,primary 19 of transformer T and wire 20 to plate 6, thence through the electron tube K to battery 13. Circuit 1; is

loosely coupled with the plate circuit by transformer T, and is from the secondary of transformer T, through wire 56, contact 57 of a relay R wire 58, condenser 22,-primary winding of atransformer T, wire 59, coil 23, and. wire 60. to the secondary oftransformer T. The circuit for the secondary of transformer T constitutes the grid circuit for an electron tube K. This circuit, which is designated a, is from the secondary of transformer T, through wire 61, condenser 46, wires 62 and 60, coil 44, and wire 68- to the secondary of transformer T. The plate circuit for electron tube K is from battery 13, through wires 14 and 67, winding 66 of relay R winding 64 of this relay and condenser 65 in multiple, wire 63, thence through electron tube K, and wire 62 to battery 13.

Relay R controls a brake application magnet M through'the medium of contact 50 in the same manner as the correspond-.

'ing magnet M is controlled ,by relay, R

in Fig. 1. The result is, that when relay R becomes deriergized, magnet M likewise becomes deiz'nergized and, causes an automo matic application of the brakes.

As in Fig. 1, the electron tube K is so con nected that it serves as a generator'of alternating current. the frequency of which depends on the frequency to which circuit a is tuned (the given frequency). The current in the plate circuit of electron tube K ,produces alternating current of the same frequency in the loosely coupled oscillating -circuit b, which circuit is normally tuned to resonance at the frequency of such current. Circuit 6 is coupled loosely with circuit 0 through the medium of transformer T, and circuit 0 is likewise tuned to res=" onance at the same frequency as circuit a. The current thus induced in circuit 0 pro duces an alternating difference of potential between the grid and filament of electron tube K, and thus produces an alternating current component'of the same frequency in the plate circuit of electron tube K,this alter natiug component being of sutlicient amplitude to effectively energize relay It. When, however, core 24 passes over one of the trackway bars D, the resonance of circuit 2) at the given frequency is destroyed so that the current which then flows in this circuit is comparatively weak. The current which is then induced in circuit a is likewise weakened, so that the current in the plate circuit of electron tube K is then insufficient to effectively energize relay-QR. The deenergization of relay R is prevented, however, if the adjacent conductor W is supplied with alternating current of the frequency to which circuit 0 is tuned. In this event, the sustained oscillations are maintained in circuit a so that the plate circuit for electron tube K carries alternating current of sufficient amplitude to energize relay R or to keep this relay energized if it is already in such'condition.

It follows fromthe foregoing that the frequency of the current supplied to the trackway conductors W by nerator G must be the same as that to w ich circuits (1 b and c are tuned.

The operation of the apparatus as shown in Fig. 2 will now be obvious. As long as core 24 is not over one of the trackway bars D, relay R will be-efi'ectively energized, so. tl1at magnet M will be energized. When the core 24 passes over one of the bars D, if the adjacent conductor W is supplied with current, relay R" will continue to be energized, but if such conductor W is not supplied with current, relay R will open and so will deener ize ma et M to cause an automatic brake application. When core 24 passes away from bar D, relayR will remain denerghed because circuit 6 includes .a contact 57 of this relay which is closed only when the relay is energized.

To permit the vehicle to proceed after 1t has been brought to a stop,-a push button 76 is provided which, when closed, closes a shunt around contact 57, and which, as in Fig. 1, is accessible only from the ground. hen this button 1:s closed, it closes circuit b, whereupon-circuit c is supplied with-current of the predetermined frequency so that relay R becomes effectively energized and will remain so after button 76 is released.

Referring now to Fig. 3, the trackway ap- 'paratus shown herein is the same as that shown in Figs. 1 and 2'. As for the apparatus on the vehicle, the oscillating circuit a which excites the gridof the electron tube K includes the coil on the core 24, this circuit being from secondar 12 of transformer T through condenser 1, wire 70, coil 23, wire 69 to secondary 12. .The plate circuit for the electron tube K is from battery 13, through wires .14 and 71, contact 72 of relay wire 73, primary of transformer T wire 74., primary 19 of transformer T Wire 20, thence through the electron tube K to battery 13. Oscillating circuit b, which is energized by virtue of transformer T is fromthe secondary of this transformer, through wire 75, condenser 46, 'wires 62 and 70, coil =14 and wire 68 to the secondary'of transformer T This circuit b constitutes the grid or exciting circuit for electron tube K. The controlof relay R by the plate circuit of electron tube K,

' when-the latter relay relay R and the control of brake application magnet M by relay R are the same as in Fig. 2'.

The plate circuit of electron tubeK will, or course, deliver alternating current of a frequency depending on the constants of circuit a and these constants'are' so chosen that the plate circuit current will be of the given frequency when coil 23 is,not in proximity to trackway bar D. The current will be of a different 23 is in proximity to a trackwayibar D, that is, when the inductancev of 1 1611 23 is increased. Circuit b is tuned to resonance at the given frequency, It follows, then,

that when core 24 is not affected by a trackway bar I), oscillations are maintained in circuit b, and the alternating current flowing in the plate circuit of electron tube K is sufiicient to energize relay R When, however, core 24 passes over one of the traokway devices D, the inductance of the circuit a is changed so that the frequency of thecurrent of electron tube K is likewise changed. Inasmuch as the current which is then delivered to circuit 1) is of a frequency different from that to which this c rcuit is b will be materially reduced and the cur rent delivered by electron tube K is then insufficient to effectively energize relay R The operation of the apparatus shownin Fig. 3 will be obvious from the explanations given hereinbefore-of the operation of the. apparatus shown in Figs. 1 and 2.- When a trackway bar D is encountered whose adjacent conductor W is deenergized, relay R will open so that the brakes will be ap-' plied. After the vehicle leaves the bar D, will remain open because the plate circuit for electron tube K includes a contact 72 or relay R which is closed only is effectively energized, and hence; circuit 6 and the plate circuit for electron tube K are then deprived of current. To permit the vehicle to proceed after being brought to rest, a push button when closed, closes a 76 is provided which, shunt around contact 72, and which, as in Figs. 1 and 2, is so located as to be accessible only from the-ground.

Although I have herein shown and described only three forms of apparatus embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appending-claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is: 4

1. Railway traiiic controlling apparatus comprising a vehicle, a circuit thereon tuned to resonance at a given frequency, means on the vehicle for supplying alternating current to said circuit, a second circuit com- .frequency when coil flowing in the plate circuit tuned, the current which wlll then flow in circuit.

fixed inductance and capacity for determining the frequency of said alternatin current, vehicle governing means on the ve icle controlled by said first circuit and arranged to be inactive when said first circuit-is tuned to said frequency, devices lo cated at intervals in the trackway for temporarily destroying the resonance of said first circuit at said frequency, means on the vehicle for keeping said governing means 7 j in inactive condition independently of said first circuit, and other devices located in the trackway adjacent said first-mentioned devices and controlled by traffic conditions in advance for causing said last-mentioned means to be efi'ective.

2; Railway traffic controlling apparatus comprising a vehicle; an electron tube thereon having'an incandescent filament, a plate, and a grid interposed between the plate and filament; a plate circuit for said electron tube including a source of current and the primaryof a transformer, means for energizing the grid of said electron tube comprisin'g'a' circuit including a condenser and the secondary of said transformer, whereby current of a given frequency is maintained in; the plate circuit, a second circuit tuned to resonance at the' given frequency and arranged to be energized inductively from said plate circuit, a relay having 'a winding.included in the second circuit, and effectively energized only when said circuit is resonant at said given frequency, a stick relay whose holding circuit is controlled bysaid relay, devices located at intervals in the trackway for temporarilychanging the inductance of the second circuit sufliciently to cause said relay to become deiinergized, a second relay on the vehicle arranged when energized to 4 close the pick-up circuit for said stick relay, other devices located in the trackway adjacent said first-mentioned devices and controlled by tratfic conditions in advance for causing said second relay to be energized, and vehicle governing means on the vehicle controlled by said stick relay.

3. Railway traflic controlling apparatus comprisi-ng a vehicle, a circuit thereon tuned to resonance at a given frequency, means on the vehicle for supplying alternating current of said given frequency to said circuit, a relay R having a winding included in said circuit which relayis energized only when said circuit is resonant at said given frequency, a stick relay whose holding circuit is controlled by said. relay R, devices located at intervals in the trackway for temporarily changing the inductance of said circuit sutficiently to cause relay R to become dei ncrgized, a relay Ron the vehicle arranged when ener ized to close the piclcup circuit for said stick relay, other devices located in the trackway adjacent said first-mentioned devices and controlled by traflic conditions 130 prising a in advance for causing relay R to be energized, and vehicle governing means on the vehicle controlled by said stick relay.

4. Railway trafiic controlling apparatus comprising a vehicle; an electron tube thereon having an incandescent filament, a plate, and a grid interposed between the filament and the plate; a plate circuit for said electron tube including a source of current and the primary of a transformer, agrid circuit for said electron tube including a condenser, a circuit (4 including said condenser and the secondary of said transformer and said circuit beingtuned to resonance at a given frequency whereby current of said frequency is maintained in the plate circuit, a circuit 6 tuned to resonance at the said given frequency and arranged to be energized inductively from said plate circuit, vehicle governing means on the vehicle controlled by said ciccuit b and arranged to be inactive when said circuit is tuned to resonance at said frequency, devices locatedat intervals in the trackway for temporarily destroying the resonance of said circuit: at said frequency, means on the vehicle for keeping said governing means in inactive condition independently of said'circuit, and other devices located in the trackway adjacent said firstmentioned devices and controlled by trafiic' conditions in advance for causing said lastmentioncd means to be effective.

5. Railway traffic controlling apparatus comprising vehicle, a circuit thereon, means for continuously supplying alternating current to said circuit, a second circuit I) receiving current inductively from the first circuit and tuned to resonance at' the frequency of such current, a relay having anenergizing' winding supplied with current from the first circuit and a secondenergizing winding supplied with current from circuit 7), said relay being eiiectively energized only when circuit 6 is resonant at said frequency, vehicle governing means on the vehicle controlled by saidgrelay and arranged to be inactive when the relay is effectively energized} devices located at intervals in the trackway for temporarily destroying the resonance of circuit 6 at said frequency, means on the vehicle for keeping said governing means in inactive condition when said relay becomes deenergized, and other devices located in the trackway adjacent said first-mentioned devices and controlled by trailicconditions in advance for causing said last-mentioned means to be efiective.

6. Railway trafiic controlling apparatus comprisin a vehicle, asource of alternating current o fixed frequency thereon, acircuit supplied with ener y from said source and comprising inductance and capacity, said circuit being tuned to resonance at theirequency of said source, a'relayha ing two,

windings one of which is connected with said source and the other with said circuit, said relay being energized only when said circuit is resonant at the frequency of. said source, vehicle governing means controlled by said relay '.and maintained in inactive condition when said relay is energized, trackway means for temporarily varying the inductance of said circuit, and means for maintaining said vehicle governing means in inactive condition independently of said circuit.

7. Railway trafiic" controlling apparatus comprising a vehicle, a-circuit b thereon tuned to resonance at a given frequency, means on the vehicle for supplying alternating current of said given'frequency to said circuit, vehicle governing means on the vehicle controlled by ,said circuit and arranged to be,inactive when the circuit is resonant at said frequency, devices located at intervals in the trackway for temporarily destraying the resonance of circuit b at said frequency, a circuit 0 on the vehicle, an electrontube having 'a grid circuit controlled by said circuit 0, means controlled by the plate circuit of said electron tube for keeping said vehicle governing means in inactive condition independently of circuit 71, and other devices located in the trackwa'y adjacent said first-mentioned devices and controlled by trafiio conditions in advance for supplying current to circuit 0.

8. Railway trafiic controlling apparatus comprising a vehicle, a circuit having fixed characteristics and a source of alternating current whose frequency is controlled thereby, a second circuit connected to said source, normally inactive vehicle governing means controlled by said second circuit; trackway means for varying the inductance of said second circuit to render said vehiclegoverning means active, and means for maintaining said vehicle governing means inactive independently of said second circuit.

9 Railway traflic controlling apparatus comprising a vehicle, a circuit thereon normally tuned to resonance at agiven frequency, vehicle governing means on the ve hicle controlled by said circuit and held in inactive condition when said-circuit is resonant at said frequency, devices located at intervals in the trackway fortemporarily destroying the resonanc of saidcircuit at said given frequency, a second circuit on the vehicle, an electron tube onithe vehicle havin -a grid circuit controlled by said secon circuit, means controlled. by the plate circuit of said electron tube for maintaining said vehicle governing means in inoperative condition irrespective of the condition of the first circuit, and other devices located in. thetraclrway and independent of said first-mentioned devices and controlled by traffic conditions in advance for supplying current to said second circuit.

10. Railway traflic governing apparatus comprising a vehicle, governing means thereon normally biased to stop the vehic a plurality of resonant circuits on the vehicle, means associating such circuits and said governing means to control the latter,

and trackway means for affecting two of said vehicle circuits, one of said trackway means being energized when the track is clear in advance, and the other being unaffected by traffic conditions.

11. Railway traffic controlling apparatus comprising a vehicle, governing means thereon biased to give a stop indication, two circuits on the vehicle either of which when energized will cause said governing means to give a proceed indication, the first of said circuits being normally energized by a source of current on the vehicle, trackway means for effectively nullifying the effect of said source in said first circuit, other traclrway means for causing the second cir cuit to be energized, and amplifying means on the vehicle for increasing the effect of said second tracirway means on said second circuit.

lQltailway trafiic controlling apparatus comprising a vehicle,a circuit thereon containing inductance and capacity, means on the vehicle for supplying alternating current to said circuit, a second circuit on the vehicle including inductance and capacity for determining the frequency of the current supplied to said first circuit, devices located at intervals in the trackway for temporarily changing the value of the inductance in said first circuit and thereby decreasin the current therein, governing means on the vehicle set into'operation by such decrease of current in the first circuit, and means governed by traiiic conditions for preventing operation of said governing means.

13. Railway traffic controlling apparatus comprising a vehicle, a source of alternating current on said vehicle, a circuit on said vehicle supplied with current from said source and containing inductance and capacity, a normally energized relay on the vehicle having two windings one of which is supplied with. current from said circuit and the other from said source independently of said circuit, devices located at intervals in the trackway for temporarily changing the value of the inductance in said circuit suiticiently to open said relay, a second relay on v the vehicle, means controlled from the trackway'for energizing said second relay, and

active condition wheneither of said relays is] energized.

14. Bailway traiiic controlling apparatus comprising a vehicle, a source of alternating current on said vehicle, a circuit on said vehicle supplied with current from said source and containing inductance and capacity, a normally energized relay on the vehicle having two windings one of which is supplied with current from said circuit and the other from said source independently ofsaid circuit, devices located at intervals in the trackway for temporarily changing the value of the inductance in said circuit sufliciently to open said relay, governing means on the, vehicle set into operation when said relay opens, and auxiliary means controlled from the trackway for preventing operation of said governing means when said relay opens.

15. Railway traffic controlling apparatus comprising a vehicle, a source-of alternating current on said vehicle, a circuit on said vehicle supplied with current from said source and containing inductance and capacity, a normally energized relay on the vehicle having :two windings one of which is supplied with current from said circuit and the other from said source independently of said circuit, devices located at intervals in the trackway for temporarily changing the value of the inductance in said circuit sutlicientlyv hicle having a holding circuit controlledhy said first relay, means controlled from the trackway for picking up said stick relay,

and governing means on the vehicle held in inactive condition when said stick relay is closed.

16. Railway trafiic controlling apparatus comprising a vehicle, governing apparatusthereon biased to give astop indication, two circuits'on the vehicle either of which when energized will cause said apparatus to give a proceed indication, an electron tube oscillator on the vehicle for normall supplying alternating current of constant requency to one of said circuits, devices located at intervals in the traclrway for efi'ectively nullifying the efi'ect of said one circuit on the governing apparatus, and other devices lo,- catedin the trackway for causing the other circuit to be energized.

In testimony whereof I a-fiix my signature in presence or" two witnesses.

LLOYD V. LEWIS.

Witnesses A. HERMAN Wnonnn, E. R. (31mm. 

